MySQL SQL选择查询和替换值

我有一个SQL查询，其中我有一些case语句和count，以便透视我的“clase x”行，它返回类似这样的结果

| Nombre Completo | Clase 1 | Clase 2|
--------------------------------------
| Example name   |   3      |    5   |
--------------------------------------

我需要的是，替换数字，如果数字大于0，则替换为是，否则替换为否。 我该怎么做？ Mysql查询：

SELECT  DISTINCT concat_ws(' ',U.firstname, U.lastname) as  Nombre_Completo,
COUNT(CASE WHEN b.name="Clase 1" THEN b.name END) Clase1,
COUNT(CASE WHEN b.name="Clase 2" THEN b.name END) Clase2,
COUNT(CASE WHEN b.name="Clase 3" THEN b.name END) Clase3,
COUNT(CASE WHEN b.name="Clase 4" THEN b.name END) Clase4,
COUNT(CASE WHEN b.name="Clase 5" THEN b.name END) Clase5,
COUNT(CASE WHEN b.name="Clase 6" THEN b.name END) Clase6,
COUNT(CASE WHEN b.name="Clase 7" THEN b.name END) Clase7,
COUNT(CASE WHEN b.name="Clase 8" THEN b.name END) Clase8,
COUNT(CASE WHEN b.name="Clase 9" THEN b.name END) Clase9,
COUNT(CASE WHEN b.name="Clase 10" THEN b.name END) Clase10,
COUNT(CASE WHEN b.name="Clase 11" THEN b.name END) Clase11,
COUNT(CASE WHEN b.name="Clase 12" THEN b.name END) Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;

使用

IF（）

测试

COUNT（）的结果

每：

在您的代码中，可以编写为：

SUM(b.name='Clase X')

因为MySql将像
b.name='Clase 1'
这样的布尔表达式计算为
1
（true）或
0
（false）。

此外，如果任何整数值
0
或
true
不同于
0
，则可以将其解释为
false
。

因此，您可以这样编写查询：

SELECT concat_ws(' ', U.firstname, U.lastname) Nombre_Completo,
       CASE WHEN SUM(b.name='Clase 1') THEN 'yes' ELSE 'no' END Clase1,
       CASE WHEN SUM(b.name='Clase 2') THEN 'yes' ELSE 'no' END Clase2,
       CASE WHEN SUM(b.name='Clase 3') THEN 'yes' ELSE 'no' END Clase3,
       CASE WHEN SUM(b.name='Clase 4') THEN 'yes' ELSE 'no' END Clase4,
       CASE WHEN SUM(b.name='Clase 5') THEN 'yes' ELSE 'no' END Clase5,
       CASE WHEN SUM(b.name='Clase 6') THEN 'yes' ELSE 'no' END Clase6,
       CASE WHEN SUM(b.name='Clase 7') THEN 'yes' ELSE 'no' END Clase7,
       CASE WHEN SUM(b.name='Clase 8') THEN 'yes' ELSE 'no' END Clase8,
       CASE WHEN SUM(b.name='Clase 9') THEN 'yes' ELSE 'no' END Clase9,
       CASE WHEN SUM(b.name='Clase 10') THEN 'yes' ELSE 'no' END Clase10,
       CASE WHEN SUM(b.name='Clase 11') THEN 'yes' ELSE 'no' END Clase11,
       CASE WHEN SUM(b.name='Clase 12') THEN 'yes' ELSE 'no' END Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;

我删除了
DISTINCT
，因为它是不需要的，因为您按Nombre_Completo进行分组

SUM(b.name='Clase X')

SELECT concat_ws(' ', U.firstname, U.lastname) Nombre_Completo,
       CASE WHEN SUM(b.name='Clase 1') THEN 'yes' ELSE 'no' END Clase1,
       CASE WHEN SUM(b.name='Clase 2') THEN 'yes' ELSE 'no' END Clase2,
       CASE WHEN SUM(b.name='Clase 3') THEN 'yes' ELSE 'no' END Clase3,
       CASE WHEN SUM(b.name='Clase 4') THEN 'yes' ELSE 'no' END Clase4,
       CASE WHEN SUM(b.name='Clase 5') THEN 'yes' ELSE 'no' END Clase5,
       CASE WHEN SUM(b.name='Clase 6') THEN 'yes' ELSE 'no' END Clase6,
       CASE WHEN SUM(b.name='Clase 7') THEN 'yes' ELSE 'no' END Clase7,
       CASE WHEN SUM(b.name='Clase 8') THEN 'yes' ELSE 'no' END Clase8,
       CASE WHEN SUM(b.name='Clase 9') THEN 'yes' ELSE 'no' END Clase9,
       CASE WHEN SUM(b.name='Clase 10') THEN 'yes' ELSE 'no' END Clase10,
       CASE WHEN SUM(b.name='Clase 11') THEN 'yes' ELSE 'no' END Clase11,
       CASE WHEN SUM(b.name='Clase 12') THEN 'yes' ELSE 'no' END Clase12
FROM mdl_logstore_standard_log as L
LEFT JOIN mdl_course as C ON L.courseid = C.id 
left JOIN mdl_user as U on L.userid = U.ID
JOIN mdl_bigbluebuttonbn AS b ON L.objectid = b.id
JOIN mdl_role_assignments AS ra ON L.userid = ra.userid
JOIN mdl_role AS r ON r.id = ra.roleid
WHERE (C.shortname LIKE '%CSG012020%') AND (ra.roleid=5)  AND (ra.roleid NOT IN (3,4))
GROUP BY Nombre_Completo;